3'3'-cGAMP is a second messenger produced in bacteria by specific dinucleotide cyclases. It contains canonical 3'5'-phosphodiester bonds and regulates chemotaxis, colonization, and other cellular functions. 3'3'-cGAMP shows weaker binding to the adapter protein stimulator of interferon genes (STING; Kd = 1.04 uM) than 2'2'-cGAMP and 2'3'-cGAMP but has similar binding affinity to 3'2'-cGAMP (Kd = 1.61 uM) and cyclic di-GMP . 3'3'-cGAMP induces IFN-beta mRNA expression in L929 cells (EC50 = 40.5 nM).